Inquisitive, intelligent, bold—kea find humans and their cast-offs every bit as intriguing as we find them. But our relationship with these cocky mountain parrots has not always been so cordial. For over a century, farmers slaughtered kea in their thousands in retribution for their attacks on sheep. Only now, with changes in high-country management and new insights into kea behaviour, are we learning to live with this spirited bird.

Magazine

Oct - Dec 1994

As the year draws towards its close, so the splen­did arch of the Milky Way—such a feature of the winter sky—lies ever lower across the horizon, carrying with it those stunning constellations Scorpius and Sagittarius.
For city dwellers, the sky overhead begins to seem almost empty. This visual desert is in part due to light pollution which brightens the sky and masks fainter stars. A recent calculation shows that almost any New Zealand town contributes more light to the night sky than did the whole of Tudor England!
But contributing to the sparseness of the stellar scene is the fact that the Galactic South Pole is now high in the sky, and our view is towards the depths of intergalactic space and away from the plane of our galaxy, where most stars are concentrated.
Three other galaxies can be seen with the naked eye. To the south are the two Magellanic Clouds, which look like small luminous clouds. They are small, irregular galaxies so closely associated with our own that they are being distorted and destroyed by our high-powered gravitational field.
Low in the northern sky lies the great Nebula in Andromeda, M31. Rather more than 22 million light years away, it appears as a ghostly elongated ellipse. Given its low surface brightness, M31 is best seen with low-magnification night glasses. Only photo­graphy can reveal anything more than a hint of the great disk of stars surrounding the centre.
All the other galaxies, including the two great concentrations of Fornax and Sculptor, need some­thing larger than a small telescope to be seen. Such a telescope—say a Newtonian reflector of 150-200 mm aperture—is within the ability of any teenager to build if he or she buys the optical parts from a local enthusiast. Sir William Herschel, working with hand tools in the late 1700s, made a series of such tel­escopes with which he was to discover not only Uranus but hundreds of star clusters and some 2500 "nebulae," many of which were galaxies.
As spring gives way to summer, the planet Saturn dominates the sky. Jupiter, Venus and Mercury, which have been such an eye-catching group in the evening sky, are now setting in the bright skyglow of sunset, and Mars is still an after-midnight object.
Saturn, first observed by Galileo with a small refractor of stunningly poor quality, immediately posed a problem. Whereas Galileo was able to see that Jupiter and Mars were spherical and thus akin to the Sun and Moon, Saturn looked different. Sometimes it appeared to him to have a large moon almost touching either side, and at other times to have "ears" attached. Over several years, he noticed that the "ears" diminished and finally disappeared.
Not until 1655 did Christiaan Huygens, with a much superior telescope, discover that the ears were rings. He also found Titan, Saturn's largest moon. Observing that the orbit of Titan is inclined to the plane of the ecliptic, Huygens argued that the planet's equator and the rings were similarly in­clined. At times we see the rings edge on, when they appear invisible (being only tens of metres thick, though 74,000 km wide), while from oblique angles they appear massive. At present, the rings are presented to us at a modest and decreasing angle as we sweep towards our interception with the plane, so are near invisible.
Saturn, like Jupiter, is a gas giant—predominantly a ball of hydrogen and helium. The only solid material is a small core of water, ammonia and methane ices mixed with silicates and metallic oxides. Saturn is unique among the planets in that it is less dense than water.
Saturn holds pride of place for the number of its satellites-21 at the last count. The smallest are so tiny and irregular that the term "moon" is inappropriate, but the largest, Titan, with a radius of 2575 km, is 800 km larger than our moon. While our moon lacks an atmos­phere, Titan is shrouded in red-brown clouds in an atmosphere of nitrogen and a small amount of methane.
Saturn itself presented the Voyager mission of 1980 with an embarrassment of information. Like Jupiter, the planet showed coloured bands at various latitudes, though the differences are subtle. These bands appear to be related to, but do not exactly correspond with, circumplanetary wind belts which blow with terrible ferocity. Between adjacent belts, relative wind speeds may be up to 500 metres per second. On earth the fiercest high altitude jet streams blow at 100 m/s, and are rela­tively short-lived events. Just how Saturnine meteorology works, what its energy sources are, and why the system is so stable are unknown.
A further puzzle is Saturn's very strong magnetic field, more than a thousand times that of Earth's and aligned with the planet's spin axis—making the magnetic and geographical poles co-incident. Accepted theory requires the magnetic axis to be at a different angle from the axis of rotation. Somehow Saturn is breaking this "rule."
Following the observation of the rings by Huygens, there was a popular theory that they were solid. One cleric even went so far as to calculate their probable population, taking both sides into consideration but overlooking the fact that the gravitational pull is towards the centre of the planet. Life on the north face of the Eiger!
In 1857, J. C. Maxwell demonstrated that the rings must be composed of small individual particles.
That the rings are not uniform has long been known. The Outer ring, which is separated from the prominent Bright ring by Cassini's division, is visible in any half-decent telescope. Larger telescopes show that the Outer or A ring is divided into two by a dark gap, Encke's division, and that inside the Bright or B ring is the faint Crepe ring which merges into the very faint D ring.
The Voyager missions not only showed these rings in breathtaking detail but revealed the presence of faint new rings. The classical rings proved to be mystifyingly complex, composed of thousands of mini-rings contain­ing braids, spirals and even traces of radial structure.
Early next century the Cassini mission will arrive at Saturn. After delivering the probe vehicle Huygens to the surface of Titan, Cassini will go into orbit around Saturn to give us a detailed inspection of this loveliest of giants, and perhaps provide answers to the many questions we still have about this comparative neighbour.

A snowflake falling slowly through the air is one of the most peaceful sights in nature, but a million billion snowflakes falling together is one of the most destructive.
A 500,000-tonne snow avalanche peeling verti­cally off a mountainside can reach speeds of over 300 kilometres per hour. So much air is displaced by the falling snow that the avalanche is preceeded by an air blast that can throw a bulldozer off a road, rip a building apart or puncture the eardrums of a by­stander.
Avalanches are a danger to skiers and climbers, and few years pass without one or two fatalities in New Zealand. But the potential for a greater disaster occurs when a road goes through an area of high avalanche risk, such as the road through the Homer Tunnel to Milford Sound.
Construction of the Homer Tunnel began in 1935, and there were three fatalities among the construction crew from two different avalanches in the first two years. Because of this, work was sus­pended during the winter, and after the tunnel was completed the road was closed during the danger­ous months of the year to avoid further accidents.
Since 1977, because of the increasing number of tourists wanting to visit Milford Sound, the road has been open through the winter, and any avalanches that fell were cleared—a hazardous job, given that the conditions which cause one avalanche will often cause another soon after. In fact, the most recent fatality occurred in 1983, when staff were clearing the debris from one avalanche when another came down on top of them.
Wayne Carran was in a bulldozer that day, and remembers clearly what happened. He was driving across the snow from the first avalanche when overseer "Pop" Andrews walked up to his machine. Wayne opened the window to talk to him. Looking over Wayne's shoulder, Pop suddenly saw an avalanche coming over the top of the cliff, and yelled "Look out!"
Wayne turned and saw the avalanche half-way down the cliff face, then turned back to Pop and shouted "Get in with me." He thinks Pop may not have heard him over the noise of the diesel engine. In the event, Pop crouched beside the bulldozer, and Wayne bent down, jam­ming his head under the steering clutches, as he feared the cab would be sheared off. The air blast upended the bulldozer, then a second later the mass of the avalanche struck, driving the ma­chine 150 metres down the road and burying it.
Wayne was upside down, but managed to switch off the bulldozer, climb out through the burst windows of the cab and dig his way up to the surface. He found Pop dead nearby.
This accident led to a change of tactics in ava­lanche control, and now there is an active pro­gramme to release heavy build-ups of snow with explosives while the road is closed.
Forecasting the weather conditions on the ridge tops where the snow falls plays a crucial role in deciding when the ava­lanche risk necessitates closing the road.
MetService forecasters are in contact with Works Civic Construction staff several times a day during periods of high risk. They forecast amounts of rain or snowfall, temperature and, most importantly, wind speed and direction at ridge top level. Because the wind concentrates snow in certain places, it has been called the archi­tect of avalanches.
Many avalanches result from new snow falling on to old snow and failing to bind strongly to the old surface, which may have an icy crust either from melting and refreezing or the effects of wind or frost.
Sometimes a weakness can even develop within the snowpack if the snow surface temperature is much lower than that of the base. Then water molecules sublimate from ice crystals near the base, move up through the snowpack as water vapour and re-deposit on ice crystals near the top. Avalanches release natu­rally because of increasing weight on the weak layer when more snow is falling or arriving with the wind, or because of temperature changes affecting the snowpack, or even because of sound waves. Artificial release above the Milford Road is achieved by dropping explosives from helicopters.
An observer looking up from the Milford Road sees mostly sheer cliffs of bare rock, but there are over 50 avalanche basins out of sight near the ridge tops. In winter, up to 20 buses a day go to and from Milford, carrying about a thousand tourists. Keeping the road safe for them requires expert knowledge of the local snow condi­tions and the weather. It also requires patience and understanding on the part of the tourist industry, which always has strong financial reasons to keep the road open.
Overseas, avalanches have long been a serious problem. It is estimated that in the European Alps over 100,000 avalanches occur each year.
Descriptions of ava­lanches go back to the third century BC, when they killed some of Hannibal's elephants and soldiers as his army crossed the Alps to attack Rome. Avalanches have taken a toll on many armies crossing mountains, and have sometimes been deliberately used as weapons of war.
In the First World War the front line between Italy and Austria ran through the Alps. An estimated 60,000 troops were killed by avalanches, many of them started deliberately. More recently, in Af­ghanistan in the 1980s, Afghani guerillas trig­gered avalanches which swept down on to Soviet troops.
In the USA, avalanches became a problem in the late 19th century when gold-miners moved into the mountains, but the worst accident occurred in 1910 near the town of Wellington in Washington State. Two trains which had been trapped in snow drifts for five days were swept away by a large avalanche which dumped both trains, three auxil­iary steam locomotives, four electric locomotives, a rotary snowplow, several boxcars, an engine shed, a water tower and telegraph wires and poles 45 metres into the Tye River Canyon, killing 96 people and leaving only 22 survivors.
The worst avalanche accident in mountaineer­ing history occurred in the Soviet Pamirs in the summer of 1990, when a massive fall of ice and snow killed 43 out of 45 climbers camped high on peak Lenin.
But perhaps the last word should be about a beneficial avalanche. Some time in the nineteenth century "a giant snowball" landed beside a poor man's cottage in Scotland. He and his family were uninjured, and when they opened the snowball they found inside "three brace of ptarmigan, six hares, four brace of grouse, a blackcock, a pheasant, three geese and two fat stags."

Homesickness and uncertainty show on the faces of Tokelauans returning to the islands. Although Tokelau is counted as part of New Zealand, living conditions in this last Pacific dependency lag far behind those in the rest of the country, and the islanders are faced with the dilemma of whether to become independent. But in this lonely tropical outpost the cool of the evening brings its own rewards: moonrise moments of timeless charm.

When the walnut stock of the McCarthy shotgun touched Captain Elch­old's cheek the fate of yet another pigeon seemed inevit­able. With the precision of a gun turret he tracked the bird across the sky and was about to pull the trig­ger. Suddenly, he stopped. The pi­geon crash-landed into the mop of a miro tree, but Elchold's attention was now elsewhere. He lowered his weapon, watching in disbelief.

Zooming in like a mouse on wings, a bumblebee prepares to gorge on a favourite food source: tree lucerne. Cast in popular imagination as quaint, cumbersome and" of no use because they don't make honey," the bumblebee's virtues as a tireless and effective pollinator are only now being appreciated and put tp work. Far from being a droning bumpkin which somehow defies the laws of gravity, the bumblebee is being heralded as the gardener's true friend.